Synthesis and Semisynthesis of Some Structural Elements of Oligo-Mannose Type N-Glycoproteins

For the construction of N-glycoprotein glycan chains, valuable potential glycosyl donors, O-α-D-mannopyranosyl-(1→2)-α-D-mannopyranose octaacetate (19) and O-α-D-mannopyranosyl-(1→2)-O-α-D-mannopyranosyl-(1→2)-α-D-mannopyranose undeca-acetate (20) were obtained in gram-scale by the acetylation and subsequent partial acetolysis of baker's yeast, without the isolation of mannan. The acetolytic products were investigated by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Octaacetates of mannobiose (1→3) (11) and (1→6) (17) were chemically synthesized.